docs: def initialize_media_descriptor(self) -> None:
          """
          Returns the media descriptor for the first media descriptor where
          the file can be found.
          """
  
          for md in self.media_descriptors:
              media_path = self.get_media_path(md)
              if media_path.is_file():
                  self.media_descriptor = md
                  return
  
          raise FileNotFoundError(
              """Cannot find media file corresponding to {}.
              Tried looking for the following files: {}.
              """.format(self.eaf_path, [self.get_media_path(md)
                                         for md in self.media_descriptors]))